Novel supports for nickel-based catalysts for the partial oxidation of methane

Zirconia-supported nickel catalysts with different amounts of aluminum (Al/Zr = 0.2, 1 and 2) were studied in this work in order to find alternative supports for nickel-based catalysts for the partial oxidation of methane. This reaction is a promising route for producing hydrogen and syngas for different applications. Samples were prepared by precipitation and impregnation techniques, characterized by several techniques and evaluated in the partial oxidation of methane in the range of 450-750 degrees C and 1 atm. It was found that aluminum affects the textural and catalytic properties of zirconia-supported nickel catalysts. The tetragonal phase of zirconia was stabilized by aluminum and gamma-alumina was also found in the aluminum-richest samples. Aluminum increased the porosity and the specific surface area of the solids. The catalytic activity also increased with the amount of aluminum in solids probably due to the stronger interaction of nickel with the support, which slowly generates active sites during the reduction step. The methane conversion and hydrogen selectivity increased with temperature, indicating no deactivation. The hydrogen to carbon monoxide molar ratio decreased due to aluminum but was not significantly affected by temperature. The coke produced was not harmful to the catalysts and aluminum affected its amount, although no simple relationship was found between these parameters. The most promising catalyst was the sample with aluminum to zirconium molar ratio of 2, which showed high activity and hydrogen selectivity and was stable under the reaction condition. (C) 2009 Elsevier B.V. All rights reserved.